A review of the beneficiation of low-grade manganese ores by magnetic separation

Magnetic separation is an effective strategy for the upgrading of a variety of lean ores, including the beneficiation of low-grade manganese ores. This work reviews 24 studies on the magnetic separation of manganese ores; 6 of these studies report both a sufficiently high Mn grade (>44% Mn) and Mn/Fe ratio (>7.5) in the concentrate as to be suitable for use as high-grade feed materials in the production of ferromanganese. Of these 24 studies, the most efficient separation and enrichment was generally achieved by the reduction roasting of the ore prior to magnetic separation, rather than the direct separation of the ore. In both cases there was sufficient evidence for correlation, depending on the mineralogy, between the Mn and Fe grades of the ore and the final concentrate grade and Mn/Fe ratio. To yield a concentrate suitable for use in ferromanganese production, it is recommended that the ore contain a minimum initial concentration of ∼25% Mn and ∼10% Fe.